DESCRIPTION

mke2fs is used to create an ext2/ext3 filesystem (usually
in a disk partition). device is the special file corre­
sponding to the device (e.g /dev/hdXX). blocks-count is
the number of blocks on the device. If omitted, mke2fs
automagically figures the file system size. If called as
mkfs.ext3 a journal is created as if the -j option was
specified.

OPTIONS

-bblock-size
Specify the size of blocks in bytes. Valid block
size vales are 1024, 2048 and 4096 bytes per block.
If omitted, mke2fs block-size is hueristically
determined by the file system size and the expected
usage of the filesystem (see the -T option). If
block-size is negative, then mke2fs will use
hueristics to determine the appropriate block size,
with the constraint that the block size will be at
least block-size bytes. This is useful for certain
hardware devices which require that the blocksize
be a multiple of 2k.
-c Check the device for bad blocks before creating the
file system. If this option is specified twice,
then a slower, destructive, read-write test is used
instead of a fast read-only test.
-ffragment-size
Specify the size of fragments in bytes.
-F Force mke2fs to run, even if the specified device
is not a block special device, or appears to be
mounted.
-gblocks-per-group
Specify the number of blocks in a block group.
There is generally no reason the user to ever set
this parameter, as the default is optimal for the
made. Be warned that is not possible to expand the
number of inodes on a filesystem after it is cre­
ated, so be careful deciding the correct value for
this parameter.
-j Create the filesystem with an ext3 journal. If the
-J option is not specified, the default journal
parameters will be used to create an appropriately
sized journal (given the size of the filesystem)
stored within the filesystem. Note that you must
be using a kernel which has ext3 support in order
to actually make use of the journal.
-Jjournal-options
Create the ext3 journal using options specified on
the command-line. Journal options are comma sepa­
rated, and may take an argument using the equals
('=') sign. The following journal options are
supported:
size=journal-size
Create an internal journal (i.e.,
stored inside the filesystem) of size
journal-size megabytes. The size of
the journal must be at least 1024
filesystem blocks (i.e., 1MB if using
1k blocks, 4MB if using 4k blocks,
etc.) and may be no more than 102,400
filesystem blocks.
device=external-journal
Attach the filesystem to the journal
block device located on external-jour­nal. The external journal must already
have been created using the command
mke2fs-Ojournal_devexternal-journal
Note that external-journal must have
been created with the same block size
as the new filesystem.
Instead of specifying a device name
directly, external-journal can also be
specified by either LABEL=label or
UUID=UUID to locate the external jour­
nal by either the volume label or UUID
stored in the ext2 superblock at the
start of the journal. Use dumpe2fs(8)
to display a journal device's volume
label and UUID. See also the -L option
of tune2fs(8).
-L Set the volume label for the filesystem.
-mreserved-blocks-percentage
Specify the percentage of the filesystem blocks
reserved for the super-user. This value defaults
to 5%.
-M Set the last mounted directory for the filesystem.
This might be useful for the sake of utilities that
key off of the last mounted directory to determine
where the filesytem should be mounted.
-n causes mke2fs to not actually create a filesystem,
but display what it would do if it were to create a
filesystem. This can be used to determine the
location of the backup superblocks for a particular
filesystem, so long as the mke2fs parameters that
were passed when the filesystem was originally cre­
ated are used again. (With the -n option added, of
course!)
-Nnumber-of-inodes
overrides the default calculation of the number of
inodes that should be reserved for the filesystem
(which is based on the number of blocks and the
bytes-per-inode ratio). This allows the user to
specify the number of desired inodes directly.
-ocreator-os
Manually override the default value of the "creator
os" field of the filesystem. Normally the creator
field is set by default to the native OS of the
mke2fs executable.
-Ofeature[,...]
Create filesystem with given features (filesystem
options). Features which are normally turned on by
default may be disabled by prefixing the feature
with a caret ('^') symbol. Currently, the
sparse_super and filetype features are turned on by
default when mke2fs is run on a system with Linux
2.2 or later (unless creator-os is set to the
Hurd). Filesystems that may need to be mounted on
pre-2.2 Linux or other kernels should be created
with -Onone (or -r0 for Linux 1.2) which will
disable these features, even if mke2fs is run on a
system which can support them.
The following filesystem options are supported:
dir_index
Use hashed b-trees to speed up lookups
must be created with the same block
size as the filesystems that will be
using it.
sparse_super
Create a filesystem with fewer
superblock backup copies (saves space
on large filesystems).
-q Quiet execution. Useful if mke2fs is run in a
script.
-rrevision
Set the filesystem revision for the new filesystem.
Note that 1.2 kernels only support revision 0
filesystems. The default is to create revision 1
filesystems.
-Rraid-options
Set raid-related options for the filesystem. Raid
options are comma separated, and may take an argu­
ment using the equals ('=') sign. The following
options are supported:
stride=stripe-size
Configure the filesystem for a RAID
array with stripe-size filesystem
blocks per stripe.
-S Write superblock and group descriptors only. This
is useful if all of the superblock and backup
superblocks are corrupted, and a last-ditch recov­
ery method is desired. It causes mke2fs to reini­
tialize the superblock and group descriptors, while
not touching the inode table and the block and
inode bitmaps. The e2fsck program should be run
immediately after this option is used, and there is
no guarantee that any data will be salvageable. It
is critical to specify the correct filesystem
blocksize when using this option, or there is no
chance of recovery.
-Tfs-type
Specify how the filesystem is going to be used, so
that mke2fs can chose optimal filesystem parameters
for that use. The supported filesystem types are:
news one inode per 4kb block
largefile one inode per megabyte
largefile4 one inode per 4 megabytes
author.

AVAILABILITY

mke2fs is part of the e2fsprogs package and is available
from http://e2fsprogs.sourceforge.net.

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